Transcript Knee Anatomy - PA

Knee Anatomy
Knee Joint
• The most poorly constructed joint
in the body. Femur round, tibia
flat.
• Comprised of four bones.
– Femur
– Tibia
– Fibula
– Patella
Femur
• Medial and
Lateral Condylesdistal ends of the
femur.
• Largest bone in
the body
Femur
• Landmarks to know
• Add. Tubercle
• Medial and Lateral
epicondyles
• Medial and lateral
condyles
• Intercondylar fossa
• Patella fossa (not
shown)
Tibia and Fibula
Fibula
•
•
•
•
•
Landmarks to know
Apex
Head
Neck
Lateral Maelleolus
Tibia
• Landmarks to know
• Intercondylar
eminence
• Medial and lateral
condyles
• Tibial tuberosity
Patella
• Patella tendonattaches to the
anterior of the
tibia. (tibial
tuberosity)
• Quadriceps
tendon-attaches
the quadriceps to
the patella.
Joints
• Tibiofemoral
– Largest joint in body
• Patellofemoral
– Patella contains the thickest cartilage
found in the body
• Superior Tibiofibular
– Any movement here is due to
movement at the ankle
Knee Stabilizers
• PRIMARY
– Medial Collateral
Ligament
– Lateral Collateral
Ligament
– Anterior Cruciate
Ligament
– Posterior Cruciate
Ligament
• SECONDARY
– Medial Meniscus
• “C” shaped
– Lateral Meniscus
• “O” shaped
Cruciate Ligaments
• Major stabilizing
ligaments in the
knee
• Anterior Cruciate
Ligament (ACL)prevents the tibia
from sliding out in
front of the femur
• Injuries caused by
hyperflexion,
internal rotation,
hyperextension
ACL
• Has Two Bundles
– Anteromedial
• Tight in flexion and extension
– Posterolateral
• Tight in extension
• Ligament is most lax between 30 –
60 degrees flexion
Posterior Cruciate
Ligament
• Prevents
posterior
translation of the
tibia on the femur
• Resists
hyperextension of
knee
• Runs from
posterior tibia to
anterior femur
PCL
• Fibers are tightest around 30
degrees flexion
– Posterolateral fibers are the last to
become tight
• Two times stronger than ACL
Collateral Ligament
• Medial Collateral
Ligament (MCL)connect the tibia
and the femur.
• A force from the
lateral side could
cause a tear.
• Valgus force
Medial Collateral Ligament
• Two layers
– Deep layer is
actually a
thickening of the
joint capsule that
blends into the
medial meniscus
– Superficial layer is
what we view as
the MCL
Collateral Ligament
• Lateral Collateral
Ligament (LCL)connect the fibula
to the femur.
• A force from the
medial side can
cause a tear of
the LCL
• Varus force
Lateral Collateral
Ligament
• Attaches to head
of fibula
• Prevents
excessive varus
and IR forces
• Tightest in
extension, loosest
after 30 degrees
flexion
Cartilage
• Articulate
Cartilage-covers
the moving parts
of the knee.
• Chronic damage
to articulate
cartilage leads to
arthritis.
Cartilage
• Meniscus- half
moon shaped
cartilage lying
between the knee
joint.
ARTICULAR DISCS
• Medial Meniscus
• Lateral Meniscus
Meniscal Blood Supply
• Each Meniscus has 3 zones
– Red Zone
• Outer 1/3: good blood supply
– Red/White Zone
• Middle 1/3: minimal blood supply
– White Zone
• Inner 1/3: avascular (no blood supply)
• Implications for injury?
Meniscal Blood Supply